Radioelectronic unit

ABSTRACT

The invention relates to electronics and can be used in construction of electronic units performing the reception and processing of signals of the satellite radio navigation systems (SRNS). The essence of the invention is that in an electronic unit comprising a multilayer printed-circuit card, the conductors intended for screening the corresponding linking signal conductor are disposed at both its external surfaces and are connected with the ground planes by means of metallized holes of interface connections made at least at the beginning and end of each screening wire to form a closed electric circuit.

TECHNICAL FIELD

The invention relates to electronics and can be used in electronic unitsintended for reception and processing of the signals of satellite radionavigational systems (SRNS).

PRIOR ART

A specific feature of the design of electronic units used for receptionand processing of SRNS signals is that they have to be incorporated intodifferent functional devices: analogue super high-frequency andhigh-frequency devices performing the processes of reception andconversion of SRNS signals, and various analog-digital and digitaldevices, such as correlators, synthesizers, synchronizers, processorsperforming the processes of correlation search, tracing and digitalprocessing of the received signals. Onboard Devices of Satellite RadioNavigation, I. I. Kudryavtsev, I. N. Mishchenko, A. I. Volynkin et al.Edited by V. S. Shebashevich, Moscow, Transport, 1988, page 112, FIG. 47and page 126, FIG. 64. Another specific feature consists in a differentdegree of integration of the electric components realizing the differentfunctions mentioned above. For example, microcircuits using a small,average or large degree of integration can be used. In this connection,when such different functional units and elements are combined in asingle, generally small-size structure, including such dissimilar unitsand elements for processing the signals, usually having differentfrequencies, a problem arises with their electromagnetic compatibility,and mutual effect on levels of spurious and induced interference.

One known technical solution to such a problem is the development of amultiunit (multicard) structure, where separate printed-circuit cardsincorporate electronic components relating to close (homogeneous)functional groups and processing signals that are similar in type andfrequency, as, for example, in the prior art structures. Onboard Devicesof Satellite Radio Navigation, I. I. Kudryavtsev, I.N.Mishchenko, A. I.Volynkin et al. Edited by V. S. Shebashevich, Moscow, Transport, 1988,p. 112, FIG. 47, Patent of Russian Federation No. 2013897, H05 K 7/00,published on May 30, 1994. In this case, the problems of reducing thespurious and induced interference can be solved by rather a simple meansbased, for example, on intercard screening. However, this way isconnected with an increase in dimensions of the structure to bedeveloped.

When the size consideration is important, monoblock structures are used,where the heterogeneous functional units and elements are incorporatedwithin the framework of a common design unit, i.e. printed-circuit card,for example, in an electronic unit of a receiver/processor of SRNSsignals, as described in Onboard Devices of Satellite Radio Navigation,I. I. Kudryavtsev, I. N. Mishchenko, A. I. Volynkin et al. Edited by V.S. Shebashevich, Moscow, Transport, 1988, p. 132, FIG. 69. The problemsoriginating from spurious and induced interference can be solved bywell-known methods consisting in screening separate functional unitswith corresponding metal screens.

Additional measures for reducing the spurious and induced interferencemay include other useful designer's technique, in particular,installation of additional external matching elements linking theprinted-circuit components with the housing of the unit, for example, asin USSR Inventor's Certificate No 1826853, 05 K 5/00, published on Nov.20, 1996, in special arrangement of the signal conductors on theprinted-circuit card, like, for example, in Patent of Russian FederationNo 2047947, 05 K 1/02, published on Nov. 10, 1995. See, Patent ofRussian Federation No. 2013897, H05 K 7/00, published on May 30, 1994,Lund P. Precision Printed-Circuit Cards. Design and Production. oscow,Energoatomizdat, 1983, p. 112-115. A special layout of grounding andpower supply conductors, for example, as in Lund P. PrecisionPrinted-Circuit Cards. Design and Production. oscow, Energoatomizdat,1983, p. 113-114 can also be used. In so doing there is no solutioncommon for solving the given problem in all cases and in each concretecase use is made of a set of designer's tools ensuring the solution ofthe problem under particular conditions.

The selected prior art for the claimed electronic unit is the electronicunit described in Majorov S. A et al., Electronic Computers. Handbook onDesign. Edited by S. A. Majorov, Moscow Sovetskoe Radio, 1975 (pp.258-261, FIG. 12.2—prior art), p. 258-261, FIG. 12.2 consisting of asingle-card structure. The electronic unit selected as a prior art is amultilayer printed-circuit card, in which the interlayer connections ofprinted conductors are carried out by means of metallized holes of theinterlayer connections, in which the external conductive layers haveconductors, bonding contact areas, and built-in electronic components,while the internal conductive layers have other conductors andmetallized ground planes and power supply planes with windows aroundmetallized holes of the interlayer connections which were notelectrically connected with these planes. For example, for the case of aprinted-circuit card with ten conductive layers, the ground plane andpower supply plane are disposed in the fourth and fifth layersrespectively.

The disposition of the ground and power supply planes in differentconductive layers of the printed-circuit card in the prior art unitallows one to solve the problem of reducing the spurious and inducedinterference. Thus, the successful solution of this problem can beattained, if the unit includes homogeneous electronic components and theprocessed signals are close on frequency as, for example, in case of thedigital computer.

DISCLOSURE OF THE INVENTION

The technical problem to be solved by the claimed invention consists inelimination by improved design the spurious and induced interference fora small-size electronic unit performing the function of areceiver/processor of the SRNS signals and made on one multilayerprinted-circuit card carrying heterogeneous (analogue, analog digital,digital) functional electronic components having of a different degreeof integration, and the frequency band of the signals processed andconverted in the signal block ranges from thousands of megaherts at theinput down to several hertz at the output.

Solving this problem allows the existing elemental base for design ofsmall-size navigational receivers/processors intended for mass customersdealing with SRNS “GLOSNASS” and “NAVSTAR” signals.

PREFERABLE EMBODIMENTS OF THE INVENTION

The essence of the invention is an electronic unit comprising amultilayer printed-circuit card, in which the interlayer connections ofthe printed conductors are carried out by means of metallized holes ofinterface connections, in which the external conductive layers haveconductors, bonding contact areas and electronic components, while theinternal conductive layers have conductors and metallized ground andpower supply planes with windows around the metallized holes ofinterface connections which are not electrically connected with theseplanes. The electronic components and printed conductors of the card aregrouped together in three serially located zones, first of whichcorresponds to the zone of allocation of the electronic componentsperforming the analog conversion of signals from the satellite radionavigational systems; the second one corresponds to the zone ofallocation of the electronic components realizing the analog-digitalconversion of signals; and the third one corresponds to the zone ofallocation of the electronic components performing the digitalconversion of signals.

The electronic components are mounted on a printed-circuit card with sixconductive layers. In the second internal conductive layer ground planesof each of the zones are formed. In the third conductive layer powersupply conductors of the first and second zones and additionalconductors of the third zone are formed. In the fourth conductive layeradditional conductors of the first and second zones and a metallizedpower supply plane of the third zone are formed. In the fifth conductivelayer a ground plane of the first zone and additional conductors of thesecond and third zones are formed. In such a case, the ground planesmade in the second conductive layer of the card are interconnected bymeans of direct ground linking conductors located according to thelayout of the linking signal conductors. Electric connections are madein the external first and sixth conductive layers of the card, with thefirst zone being surrounded along its perimeter by screening wiresplaced opposite to each other on the first and sixth conductive layersof the card. The screening wires are connected to each other and to theground planes of the given zone in the second and fifth conductivelayers of the card by means of metallized holes made in the interfaceconnections to form a closed electric circuit. The screening wires havebreaks for passing the respective linking signal conductors, the pointsof breaks of the screening wires in the first and sixth conductivelayers of the card correspond to the continuous metallized portions ofthe ground planes in the second and fifth layers of the card.

In the claimed electronic unit the width of the ground linkingconductors performing the interconnection of the ground planes in thesecond conductive layer of the card are selected to be not less than 1mm.

In the claimed electronic unit the conductors intended for screening thecorresponding linking signal conductor are placed at both sides thereofand are connected to the ground planes by means of the metallized holesof the interface connections made at least at the beginning and end ofeach screening wire to form a closed electric circuit, the distancebetween the metallized holes not exceeding 5 mm.

In the claimed electronic unit the width of the screening wires madealong the perimeter of the first zone in the first and sixth conductivelayers of the card is selected to be not less than 2 mm.

In the claimed electronic unit the distance between the metallized holesof the interface connections interconnecting the screening wires in thefirst and sixth conductive layers of the cards and to the ground planesin the second and fifth conductive layers of the card does not exceed 5mm.

The essence of the invention, its implementation, and use in industrialapplication are explained using an example of a structure of anelectronic unit for a navigational receiver/processor intended fordetermining the navigational parameters by SRNS signals of the“GLOSNASS” and “NAVSTAR” systems. The essence of the invention isillustrated by the accompanying drawings in FIGS. 1-9.

FIG. 1 is a sectional view of the printed-circuit card of a electronicunit with six conductive layers (the layout of the conductors andmetallized holes of the interface connections is conditional);

FIG. 2 illustrates an example of grouping the electronic componentsmounted in the first conductive layer of the card of the electronic unitin three sequentially located zones (a view from the elements of thefirst layer, the printed conductors are not shown);

FIG. 3 is an example illustrating the grouping the electronic componentsmounted in the six conductive layer of the card of the electronic unitin three sequentially located zones (a view from the elements of thefirst layer, the printed conductors are not shown);

FIG. 4 is an example of a printing pattern of the first (external)conductive layer of the card of the electronic unit;

FIG. 5 is an example of a printing pattern of the second conductivelayer of the card of the electronic unit (a view on the side of thefirst layer, the layers being partially cutaway);

FIG. 6 is an example of a printing pattern of the third conductive layerof the card of the electronic unit (a view on the side of the firstlayer, the layers being partially cutaway);

FIG. 7 is an example of a printing pattern of the fourth conductivelayer of the card of the electronic unit (a view on the side of thefirst layer, the layers being partially cutaway);

FIG. 8 is an example of a printing pattern of the fifth conductive layerof the card of the electronic unit (a view on the side of the firstlayer, the layers being partially cutaway); and

FIG. 9 is an example of a printing pattern of the sixth (external)conductive layer of the card of the SRNS electronic unit (a view on theside of the first layer, the layers being partially cutaway).

The claimed electronic unit, as exemplified in FIGS. 1-9, comprises amultilayer printed-circuit card 1 with six conductive layers, whosefirst external conductive layer 2 will forms a face of the card 1, whilethe sixth external conductive layer 3 forms a back side of the card 1.The internal conductive layers of the card 1, namely, the secondconductive layer 4, third conductive layer 5, fourth conductive layer 6and fifth a conductive layer 7 of the card 1 are separated from eachother and from the external conductive layers 2 and 3 by insulatinglayers 8 (FIG. 1).

Formed in the external conductive layers 2 and 3 of the card 1 areprinted bonding contact areas 9, printed conductors 10, and electroniccomponents 11 (FIGS. 1-3). Formed in the internal conductive layers 4-7of the card 1 are printed conductors only (FIGS. 5-8). The interfaceconnections of the printed conductors of the card 1 are implemented bymeans of metallized holes 12 of the interface connections.

In FIG. 1, as an example of making the metallized holes 12 in theinterface connections, there are shown holes connecting the conductorsof the first 2, sixth 3, second 4, and fifth 7 conductive layers, aswell as the first 2, sixth 3, and fourth 6 conductive layers.

The mounting of the electronic components on the card 1 is accomplishedby using surface mounting technique to solve the problem of installing agreat number of elements on a small area.

In the considered example of implementation of the electronic unit, i.e.The SRNS receiver/processor module, the electronic components andprinted conductors of the card 1 are grouped together in threesequentially located zones 13, 14 and 15 (FIGS. 2-9).

The first zone 13 of the card 1 corresponds to the zone of allocation ofthe electronic components performing the analog conversion of the SRNSsignals, for example, of the electronic components of a low degree ofintegration similar to chips of the MGA-87563 HEWLETT-PACKARD type, andthe electronic components of a moderate degree of integration similar tochips of the MC13142D MOTOROLA and UPC2753GR NEC type.

The second zone 14 the card 1 corresponds to the zone of allocation ofthe electronic components performing the analog-digital conversion ofsignals, for example, to the electronic components of a moderate degreeof integration similar to chips of the MAX962ECA MAXIM type.

The third zone 15 the card 1 corresponds to the zone of allocation ofthe electronic components performing the digital conversion of signals,for example, to the electronic components of a super high degree ofintegration similar to chips of the TMS320 LC203-40 TEXAC INSTRUMENTS(processor) and ASIC SAMSUNG (digital correlator) types; the electroniccomponents of a large degree of integration similar to chips of theKM616V1002AT-15 SAMSUNG (ROM) type; the electronic components of amoderate degree of integration similar to chips of the DS1302S DALLAS(timer) type; and the electronic components of a small degree ofintegration similar to chips of the MAX604CSA MAXIM (stabilizer) type.

The printed conductors of the internal conductive layers of the card 1are distributed as follows.

In the second conductive layer 4 of the card 1, the ground planes 16, 17and 18 are formed in all three zones 13, 14, 15 (FIG. 5).

In the third conductive layer 5 of the card 1, power supply conductors19, 20 of the first and second zones 13, 14 and additional conductors ofthe 21 third zone 15 are formed (FIG. 6).

In the fourth conductive layer 6 of the printed-circuit card 1,additional conductors 22, 23 of the first and second zones 13, 14 andmetallized plane 24 of the power supply of the third zone 15 are formed(FIG. 7).

In the fifth conductive layer 7 of the printed-circuit card 1, a groundplane 25 of the first zone 13 and additional conductors 26, 27 of thesecond and third zones 14, 15 are formed (FIG. 8).

The ground planes 16, 17, 18 formed in the second conductive layer 4 ofthe card 1 are interconnected by direct ground linking conductors 28(FIG. 5). The width of the ground linking conductors 28 is not less than1 mm.

The ground linking conductors 28 (FIG. 5) are located according to thelayout of the linking signal conductors 29 electrically connecting thezones in the external first 2 and sixth 3 conductive layers of the card1 (FIGS. 4, 9).

Individual linking signal conductors 29 can be screened with the help ofadditional conductors 30 connected to the corresponding ground planes.Such screening can be effected, for example, with respect to the linkingsignal conductors carrying signals with sharp edges or having a signallevel significantly differing from the signal level of the adjacentconductors. FIG. 4 shows an example of the screening of the linkingsignal conductors 29 located in the first conductive layer 2. Theconductors 30 intended for screening a respective signal linkingconductor 29 are located on both its sides and are connected to theground planes to form a closed electric circuit. The connection to theground planes is carried out with the help of the correspondingmetallized holes of the interface connections made at least at thebeginning and end of the conductors 30 at a distance of not more than 5mm from each other.

The first zone 13 is surrounded along its perimeter by screening wires31, located opposite to each other respectively in the first 2 and sixth3 conductive layers of the card 1 (FIGS. 4, 9). The width of thescreening wires 31 is not less than 2 mm. The screening wires 31 areinterconnected and connected to the ground planes 16, 25 in the second 4and fifth 5 conductive layers of the card 1 by means of metallized holesmade therein to form a closed electric circuit. The distance betweenthese metallized holes does not exceed 5 mm.

The screening wires 31 have breaks 32 for passing the correspondinglinking signal conductors 29 (FIGS. 4, 9). The break points 32 of thescreening wires 31 in the first 2 and sixth 3 conductive layers of thecard 1 correspond to continuous metallized portions 33 of the groundplanes 16 and 25 in the second 2 and fifth 7 conductive layers (FIGS. 5,8).

The above-described design measures ensure necessary protection againstspurious and induced interference of the electronic components in thefirst zone 13 which is most likely to induce noise and interference, inwhich case the presence of the metallized portions 33 the ground planes16, 25, corresponding to breaks 32 in the screening wires 31 ensureoptimization of the return circuits for the signal circuits performingthe electrical links between the zones. These measures of protectionfrom spurious and induced interference are most effective in combinationwith the claimed layout of the ground planes and power supply conductorsin different conductive layers of the card, thus providing the necessaryscreening.

To exclude undesirable short circuits between the metallized holes 12 ofthe interface connections by the metallized ground planes 16-18, 25, andthe power supply plane 24, at the respective places of these planesthere are made windows 34 having no metal film (FIG. 1) for allocationof the metallized holes 12.

To connect the claimed electronic unit to the external output equipmentand a power supply source, a low-frequency connector 35 is mounted onthe face of the printed-circuit card 1 (FIG. 2).

To connect the electronic unit to a source of input signals, ahigh-frequency connector 36 is installed on the face of theprinted-circuit card 1 (FIG. 2).

For operation of the claimed electronic unit, the connector 35 isconnected to the power supply and other peripherals/such as a controlpanel or an indicator of navigational parameters etc. necessary foroperation of the unit. The connector 36 is connected to a source ofinput signals, for example, a receiving antenna cable (not shown).

The input signals of the claimed electronic unit representing analogpseudonoise (broadband) SRNS signals with frequencies in a range from1200 MHz up to 1700 MHz are applied through the connector 36 to theelectronic components of the first zone 13 of the printed-circuit card1, where they are amplified, filtered from interference and subjected toconversion with a decrease of frequency up to dozens of megaherts. Thesignals thus transformed in the first zone 13 of the printed-circuitcard 1 are subjected to multichannel analog-digital processing in thesecond functional zone 14, and then subjected to correlation processingin the digital processor formed by the electronic components of thethird zone 15.

Therefore, in the claimed electronic unit the signals during theprocessing sequentially pass from one zone of the printed-circuit card 1to another, undergoing changes in frequency from thousands of megahertsat the input of the first zone 13 (zone of allocation of the electroniccomponents performing the analog conversion of signals) down to severalhertz at the output of the third zone 15 (zones of allocation of theelectronic components performing the digital conversion of signals).

In this case, due to a combination of the offered design measurescomprising the claimed grouping of the electronic components and theprinted conductors in zones, the claimed layout of the metallized groundsupply planes in zones and layers of the card 1, the claimed screeningof the first zone 13, as well as claimed execution of the links betweenthe zones by means of the linking signal conductors 29 and the groundlinking conductors 28, the claimed electronic unit provides suppressionof the spurious and induced interference under predetermined conditionsof an essential difference in a character and frequency of the signalsand the degree of integration of the electronic components.

Thus, in the claimed electronic unit incorporating the offered designmeasures, there is provided optimization of the return circuits ofpassing the signals interlinking various zones, thereby minimizing thespurious induced interference in the unit. In particular, the width ofthe ground linking conductors 28 (not less than 1 mm) is selected from acondition of minimization of losses in return circuits of the loop forpassing the signals and lowering of their susceptibility to effect ofradiation and cross interference at the expense of exception ofnon-optimal current paths having additional inductance. The minimizationof losses in the return circuits of the loop for passing the signals isalso positively effected by the offered execution and layout of themetallized ground planes 16, 17, 18, 25, and metallized power supplyplane 24, which provide in the claimed electronic unit the optimalreturn circuits corresponding to the circuits for passing the signals inthe unit, exclude generation of parasitic current loops characterized byparasitic inductances and a noise sensitivity, and also ensure theminimum possible resistance to a direct current so that the voltage dropin the circuits of the card is practically excluded.

The above design parameters: a width of the screening wires 31 of notless than 2 mm, a pitch of maximum 5 mm between the metallized holes ofthe interface connections made in the screening wires 30 and 31,characterize the implementation of the claimed unit in the bestembodiment of the invention.

Thus, the combination of the above-considered design measures allows theclaimed electronic unit to solve the problem of elimination of spuriousand induced interference under specific conditions, when a multilayerprinted-circuit card of the unit carries different electronic componentsof a various degree of integration constituting a navigational SRNSreceiver/processor, where the frequencies of signals being processedvary from thousands megaherts at the input down to several hertz at theoutput.

The experiments which have been carried out with the prototype models ofthe electronic units of the claimed structure have shown that theelimination of spurious and induced interference required underconditions of operation of the units processing the SRNS “GLOSNASS” and“NAVSTAR” signals in various combinations thereof and in all frequencyranges is ensured.

Therefore, it is clear from the above that the claimed electronic unittechnically is feasible, can be made in an industrial scope and solvesthe technical problem of elimination of spurious and inducedinterference under specific conditions of implementation of a small-sizeelectronic unit performing the function of a navigational SRNSreceiver/processor realized on a single multilayer printed-circuit cardcarrying heterogeneous (analog, analog-digital, digital) functionalelectronic components of a different degree of integration. Thefrequency band of the signals to be processed and converted in the unitlies in a range from thousands of megaherts at the input to severalhertz at the output.

References

1. Onboard Devices of Satellite Radio Navigation, I. I. Kudryavtsev, I.N. Mishchenko, A. I. Volynkin et al. Edited by V. S. Shebashevich,Moscow, Transport, 1988.

2. Patent of Russian Federation No. 2013897, H05 K 7/00, published onMay 30, 1994.

3. USSR Inventor's Certificate No 1826853, 05 K 5/00, published on Nov.20, 1996.

4. Patent of Russian Federation No 2047947, 05 K 1/02, published on Nov.10, 1995.

5. Lund P. Precision Printed-Circuit Cards. Design and Production.oscow, Energoatomizdat, 1983.

6. Majorov S. A et al., Electronic Computers. Handbook on Design. Editedby S. A. Majorov, Moscow Sovetskoe Radio, 1975 (pp.258-261, FIG.12.2—prior art).

What is claimed is:
 1. An electronic unit comprising a multilayerprinted-circuit card, in which the interface connections of the printedconductors are carried out by means of the metallized holes of theinterface connections, in which the external conductive layers haveconductors, contact areas and electronic components, and the internalconductive layers have conductors and metallized ground and power supplyplanes with windows around the metallized holes of the interfaceconnections which are not electrically connected with these planes,characterized in that the electronic components and printed conductorsof the card are grouped together in three sequentially located zones,first of which corresponds to the zone of allocation of the electroniccomponents performing the analog conversion of the signals from thesatellite radio navigation systems, second one corresponds to the zoneof allocation of the electronic components performing the analog-digitalconversion of the signals, and third one corresponds to the zone ofallocation of the electronic components performing the digitalconversion of the signals, the electronic components being mounted on aprinted-circuit card with six conductive layers, where the internalsecond conductive layer has ground planes in each zone, the thirdconductive layer has a power supply conductors of the first and secondzones and additional conductors of the third zone, the fourth conductivelayer has additional conductors of the first and second zones and ametallized power supply plane of the third zone, the fifth conductivelayer has a ground plane of the first zone and additional conductors ofthe second and third zones, in which case the ground planes made in thesecond conductive layer of the card are interconnected by means ofdirect ground linking conductors located according to the layout of thelinking signal conductors effecting electrical connections between thezones in the external first and sixth conductive layers of the card, thefirst zone being surrounded along its perimeter by screening wiresallocated opposite to each other in the first and sixth conductivelayers of the card, said screening wires being interconnected andconnected to the ground planes of the given zone in the second and fifthconductive layers of the card by means of the metallized holes madetherein to form a closed electric circuit; said screening wires havingbreaks for passing the respective linking signal conductors, in whichcase the breaks of the screening wires in the first and sixth conductivelayers of the card correspond to the continuous metallized portions ofthe ground planes in the second and fifth layers of the card.
 2. Theelectronic unit according to claim 1, characterized in that the width ofthe ground linking conductors interconnecting the ground planes in thesecond conductive layer of the card is selected to be not less than 1mm.
 3. The electronic unit according to claim 1, characterized in thatthe conductors intended for screening the corresponding linking signalconductor are placed at both its sides and connected to the groundplanes by means of the metallized holes of the interface connectionsmade at least at the beginning and end of each screening wires to form aclosed electric circuit, the distance between the metallized holes beingmaximum 5 mm.
 4. The electronic unit according to claim 1, characterizedin that the width of the screening wires made along the perimeter of thefirst zone in the first and sixth conductive layers of the card isselected to be at least 2 mm.
 5. The electronic unit according to claim1, characterized in that the distance between the metallized holes ofthe interface connections interlinking the screening conductors madealong the perimeter of the first and sixth conductive layers of the cardand connecting them to the ground planes in the second and fifthconductive layers of the card does not exceed 5 mm.